// SPDX-License-Identifier: LGPL-2.0-or-later
// Copyright © EDF R&D / TELECOM ParisTech (ENST-TSI)

#pragma once

//Local
#include "DistanceComputationTools.h"
#include "ReferenceCloud.h"

//system
#include <cstdint>

namespace CCCoreLib
{
	class GenericIndexedCloudPersist;
	class GenericProgressCallback;

	//! Proper KD-tree implementation
	class CC_CORE_LIB_API TrueKdTree
	{
	public:

		//Warning: never pass a 'constant initializer' by reference
		static const uint8_t X_DIM = 0;
		static const uint8_t Y_DIM = 1;
		static const uint8_t Z_DIM = 2;
		static const uint8_t NODE_TYPE = 0;
		static const uint8_t LEAF_TYPE = 1;

		//! Tree base node
		class BaseNode
		{
		public:
			explicit BaseNode(uint8_t nodeType) : parent(nullptr), type(nodeType) {}
			virtual ~BaseNode() = default;

			bool isNode() const { return type == NODE_TYPE; }
			bool isLeaf() const { return type == LEAF_TYPE; }

		public:

			//Warning: put the non aligned members (< 4 bytes) at the end to avoid too much alignment padding!
			BaseNode* parent;					//8 bytes

		protected:
			const uint8_t type;					//1 byte (+ 3 for alignment)

			//Total								//12 bytes
		};

		//! Tree node
		class Node : public BaseNode
		{
		public:

			//Warning: put the non aligned members (< 4 bytes) at the end to avoid too much alignment padding!
			PointCoordinateType splitValue;		//4 bytes
			BaseNode* leftChild;				//8 bytes
			BaseNode* rightChild;				//8 bytes
			uint8_t splitDim;					//1 byte (+ 3 bytes for alignment)

			//Total								//24 bytes (+ 12 for father)

			Node()
				: BaseNode(NODE_TYPE)
				, splitValue(0)
				, leftChild(nullptr)
				, rightChild(nullptr)
				, splitDim(X_DIM)
			{}

			~Node() override
			{
				delete leftChild;
				delete rightChild;
			}
		};

		//! Tree leaf
		class Leaf : public BaseNode
		{
		public:

			//Warning: put the non aligned members (< 4 bytes) at the end to avoid too much alignment padding!
			ReferenceCloud* points;				// 8 bytes
			PointCoordinateType planeEq[4];		//16 bytes
			ScalarType error;					// 4 bytes
			int userData;						// 4 bytes

			//Total								//32 bytes (+ 12 for father)

			//! Constructor
			/** The Leaf class takes ownership of its associated subset
			**/
			Leaf(ReferenceCloud* set, const PointCoordinateType planeEquation[], ScalarType _error)
				: BaseNode(LEAF_TYPE)
				, points(set)
				, error(_error)
				, userData(0)
			{
				memcpy(planeEq, planeEquation, sizeof(PointCoordinateType) * 4);
			}

			~Leaf() override
			{
				delete points;
			}
		};

		//! A vector of leaves
		using LeafVector = std::vector<Leaf *>;

		//! Default constructor
		explicit TrueKdTree(GenericIndexedCloudPersist* cloud);

		//! Destructor
		~TrueKdTree();

		//! Returns the associated cloud
		inline GenericIndexedCloudPersist* associatedCloud() const { return m_associatedCloud; }

		//! Builds KD-tree
		/** \param maxError maximum error per cell (relatively to the best LS plane fit)
			\param errorMeasure error measurement
			\param minPointCountPerCell minimum number of points per cell (can't be smaller than 3)
			\param maxPointCountPerCell maximum number of points per cell (speed-up - ignored if < 6)
			\param progressCb the client application can get some notification of the process progress through this callback mechanism (see GenericProgressCallback)
		**/
		bool build(	double maxError,
					DistanceComputationTools::ERROR_MEASURES errorMeasure = DistanceComputationTools::RMS,
					unsigned minPointCountPerCell = 3,
					unsigned maxPointCountPerCell = 0,
					GenericProgressCallback* progressCb = nullptr);

		//! Clears structure
		void clear();

		//! Returns max error threshold used for planarity-based split strategy
		inline double getMaxError() const { return m_maxError; }

		//! Returns max error estimator used for planarity-based split strategy
		inline DistanceComputationTools::ERROR_MEASURES getMaxErrorType() const { return m_errorMeasure; }

		//! Returns all leaf nodes
		bool getLeaves(LeafVector& leaves) const;

	protected:

		//! Recursive split process
		BaseNode* split(ReferenceCloud* subset);

		//! Root node
		BaseNode* m_root;

		//! Associated cloud
		GenericIndexedCloudPersist* m_associatedCloud;

		//! Max error for planarity-based split strategy (see m_errorMeasure)
		double m_maxError;

		//! Error measurement
		DistanceComputationTools::ERROR_MEASURES m_errorMeasure;

		//! Min number of points per cell (speed-up)
		/** Can't be < 3
		**/
		unsigned m_minPointCountPerCell;

		//! Max number of points per cell (speed-up)
		/** Ignored if < 6
		**/
		unsigned m_maxPointCountPerCell;
	};
}
